Sunday, 24 October 2010

(1) Crab Apple - Malus sylvestris

Background

The apple is a genus (Malus) of about 30-35 species of flowering plant in the Rosaceae family. The term "apple" also refers to the fruit of these trees; the term generalises the variety of fruits and particularly refers to the species Malus domestica, the domesticated orchard or table apple (1).
The species Malus sylvestris, commonly known as the "crab apple" or the "European wild apple", is a forest apple, the wild variety; they are generally small and sour, unpalatable fruit (1)(2). This species is native to Europe, from as far south as Spain, Italy and Greece, to as far north as Scandinavia and Russia (2).

Malus sylvestris has been shown, through recent DNA analysis, to contribute to the ancestry of M. domestica, however in older apple cultivars the evidence is lacking slightly (1)(2).

Nutritional and Medicinal Background

The proverb: "An apple a day keeps the doctor away" addresses the health benefits of the fruit, and dates back to 19th century Wales, however the benefits of the fruit were known and used long before that time (3).

Apples are a rich source of phytochemicals, and epidemiological stuides have linked the consumption of apples with reduced risk of some cancers, cardiovascular disease, asthma, and diabetes (4). In the labratory, apples have been found to have very strong antioxidant activity, inhibit cancer cell proliferation, decrease lipid oxidation, and lower LDL (low-density lipoprotein) cholesterol (4). Apples contain a variety of phytochemicals, including quercetin, catechin, phloridzin, epicatechin, procyanidin B2 and chlorogenic acid, all of which are strong antioxidants (4).

Antioxidants are molecules capable of slowing or preventing reactions promoted by oxgen or peroxides (5), in nutritional terms, antioxidants act against the effects of free radicals. A free radical is an atom or group of atoms with at least one unpaired electron - usually oxygen - that aims to stablisie itself by "stealing" an electron from a nearby molecule; "in the body free radicals are high-energy particles that ricochet wildly and damage cells" (6).

The phytochemical composition of apples varies greatly between different varieties of apples, and there are also small changes in phytochemicals during the maturation and ripening of the fruit; the skin and the flesh also show distinct differences; storage has little to no effect on apple phytochemicals, however processing can greatly affect apple phytochemicals (4). Phytochemicals are non-nutrient plant compounds, a significant source of such found in apples are referred to as flavonoids (4).

Flavonoids are a large class of brightly coloured, water soluble plant pigments (7), collectively they are also known as Vitamin P and citrin (8). They are potent antioxidants produced by plants to protect themselves from bacteria, parasites and cell damage (9). In the body they improve immune function by supporting the cells and internal systems, and prevent disease and some cancers (13).

Apple juice concentrate has been found to increase the prodcution of the neurotransmitter acetylcholine in mine studies, providing a potential mechanism for the "prevention of the decline in cognitive performance that accompanies dietary and genetic deficiencies and aging". Other studies have shown an "alleviation of oxidative damage and cognitive decline" in mice after the administation of apple juice (3). Apple polyphenol extracts have been highlighted in new research, as a prevention and possible cure for the oxidative damage associated with Alzheimer's disease, Parkinson's disease, and other neurodegenerative conditions (10). In one study, apples with skin (where the concentrations of polyphenols are highest) reversed age-related brain function decline in rats (10).

Apples also contain a substance called pectin, many other fruits also contain this compound, however apples contain very high concentrations (11). Pectin is defined as any of a group of white, amorphous, complex carbohydrates that occur in ripe fruits and certain vegetables; raw apples have been found to be the richest source of fruit pectin (12). Protopectin is present in unripe fruits, and is converted to pectin as the fruit ripens; in overripe fruits, the pectin becomes pectic acid (12).

Pectin's primary use is as a treatment for digestive disorders, it is a source of water soluble fibre - which has a gel-forming effect when mixed with water, and is a source of dietary fibre (12). In addition to regulating bowel movements, apple pection can also be helpful for people with colitis, irritable bowel disease, and other digestive disorders (11). Research in Japan has found that apple pectin can decrease the chances of malignant colon disease (12).
Apples also contain malic and tartaric acids that inhibit fermentation in the intestines, along with pectin, which encourages growth of beneficial bacteria in the digestive tract, this allows natural and comfortable elimination of the bowels (13).
Study's at the University of California have shown pectin to be useful at reducing LDL cholesterol in the blood, beneficial for subjects that suffer from coronary heart disease or have the disease in their family history (13). Pectin has also been shown to reduce blood sugar, and therefore is an useful food stuff for those suffering from diabetes (13).

Apples have an high internal water content, and are useful for reducing fever through their cooling and moistening properties (13). Steamed apples sweetened with honey are also beneficial for a dry cough and may help to remove mucous from the lungs (13).

Eating raw apples can also prevent against dental caries, as they give the gums a healthy massage and clean the teeth (13).

Nutritionally, unpeeled apples provide their most plentiful nutrients just underneath the skin, they are a good source of ptassium, folic acid, with trace volumes of B vitamins, iron, magnesium and zinc (13). Crab apples are listed as having very little vitamin C content (compared weight for weight to modern apples) (14). This measurement may not necessarily apply to all species of wild crab apple, such as M. sylvestris (14).

Medieval Medicinal Uses

In the ancient herbals the crab apple was revered as a medicine for oils, abscesses, splinters and wounds, and for coughs and colds and a host of other ailments ranging from acne to kidney ailments (15). Many dishes made with apples, and apple blossoms; the crab apples, roasted, drenched in honey and dried, were used by the monks and physicians as treatment for diarrhoea, dysentery and gallstones (15). In the spring they gathered the blossoms and perserved them in vinegar for drawing poultices and for beestings and other insect bites (15).